This invention relates to apparatus for comminuting solid waste materials such as plastic sheet material.
The manufacture and forming of many products from plastic produces significant amounts of plastic waste material. Applicant has previously invented several unique apparatus for comminuting severable waste material, particularly plastic sheet material, into small, rather uniform particles or pieces that can be readily recycled or disposed of in an environmentally acceptable manner. Several generations of product line have been sold by Irwin Research and Development, Inc., under the product name xe2x80x9cChesawxe2x80x9d and have gained commercial success. One such prior invention is the subject of the Irwin, et al, U.S. Pat. No. 4,687,144 granted Aug. 18, 1987. Other such prior inventions are the subject of U.S. Pat. Nos. 5,836,527; 5,860,607; and 5,893,523.
The first prior invention of U.S. Pat. No. 4,687,144 was a vast improvement over various types of hammermills that had previously been used. The hammermills were quite bulky, extremely noisy, and prone to substantial damage when the mill received foreign material that it could not comminute. Although such prior Irwin, et al, invention was a vast improvement and was commercially successful, particularly in view of hammermills, it was rather expensive to manufacture and sometimes noisy in operation when processing certain materials. Furthermore, it was unable to satisfactorily comminute rather high density plastic materials.
The remaining prior inventions identified above were directed to improvements over the invention of U.S. Pat. No. 4,687,144. Such improvements were directed to improving the amount of comminuted material that could be generated in a given amount of time, to improve the manner in which the comminuting apparatus operated, and/or to enhance the ability of the comminuting apparatus to efficiently subdivide pieces of material that are otherwise difficult to comminute.
As an example, U.S. Pat. No. 5,836,527 was an improvement over the invention of U.S. Pat. No. 4,687,144. More particularly, an improved comminuting apparatus is provided which can significantly increase the amount of comminuted material produced in a given amount of time. Such device is relatively less expensive to manufacture, and is quieter to operate. Such apparatus provides an ability to comminute a wider variety of solid waste materials. More particularly, the solid waste comminuting apparatus carries material that is severed in the device via an airstream through a fan. Subdivided pieces of material are directed via the fan to a separator screen which is mounted within a centrifugal housing. The airstream carries small pieces through the separator screen into an outer volute chamber for discharge from the apparatus. Large pieces which are not capable of passing through the separator screen are recycled through a recycle outlet and a recycle conduit back to scissor rolls of the device for further size reduction. However, the complexity of the apparatus and the number of parts needed to construct the apparatus increased over the device of U.S. Pat. No. 4,687,144, which has proven undesirable for certain applications.
As another example, U.S. Pat. No. 5,860,607 is directed to an apparatus for comminuting waste materials, and includes a feed roll for feeding a continuous sheet of waste material into a shear intake manifold at a desired line speed and directing the waste material to scissor rolls. An additional feature includes a screw conveyor for recirculating subdivided pieces of comminuted material. More particularly, a feed roll delivers solid waste material into overlapping scissor rolls at a desired line speed. A pneumatic conveyor, in the form of an Archimedes screw, delivers the subdivided pieces of comminuted material for sorting and reprocessing. However, this improvement also increased the complexity of the comminuting apparatus, requiring a feed roll and a screw conveyor in addition to a pair of scissor rolls.
As yet another example, U.S. Pat. No. 5,893,523 is directed to an apparatus for comminuting waste material having feed roll delivery features. A feed roll is rotatably carried by a frame for directing waste material to a set of overlapping scissor rolls which shear waste material into subdivided pieces as the material passes between the scissor rolls. A separator screen is carried by the frame in association with at least one of the scissor rolls for separating subdivided pieces having a size less than a predetermined size, and for recirculating subdivided pieces having a size greater than a predetermined size. However, a separate feed roll is needed in addition to a pair of scissor rolls.
The present invention provides a vastly improved comminuting apparatus that is not only able to process significantly greater amounts of material in a given time, it is also better able to recirculate and sort severed solid waste material utilizing an apparatus that is formed with a simplified construction having fewer moving parts, proving more reliable, less costly to manufacture, and maintain and repair, and is more efficient to operate. It is also better able to sever a wider variety of different types of materials over a broader range of line speeds, in a feed-controlled manner from a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to feed solid waste material into the comminuting apparatus in a relatively efficient and cost-effective manner, while also being able to handle a wide variety of severable materials.
The present invention provides a vastly improved comminuting apparatus that is also better able to recirculate and sort severed solid waste material in the separator screen particularly in an apparatus having a simplified construction with fewer parts, which is less costly to manufacture, maintain and repair, and is more reliable. It is also better able to sever the material at a desired speed, or line speed, in a feed-controlled manner from a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to feed solid waste material into the comminuting apparatus in a feed-controlled manner.
A self-feeding comminuting apparatus is provided having improved drive motor and recirculation features. According to one improvement, a pair of overlapping scissor rolls cooperate to feed waste material beneath and between the pair of scissor rolls to a recycle manifold section. The recycle manifold section delivers subdivided pieces to one of the scissor rolls to recycle the subdivided pieces for sorting and/or recirculation between the pair of scissor rolls for further subdividing. According to another feature, a set of overlapping scissor rolls includes a first scissor roll driven by a first drive motor at a substantially variable operating speed, and a second scissor roll driven by a second drive motor at a substantially constant operating speed. According to one aspect of the invention, an apparatus is provided for comminuting solid waste material. The apparatus includes a frame, a set of overlapping scissor rolls, a separator screen and a recycle manifold section. The frame has an enclosure with an entrance for receiving solid waste material. The set of overlapping scissor rolls is rotatably mounted within the enclosure for shearing the waste material into subdivided pieces when the material passes between the scissor rolls. Each scissor roll has a substantially horizontal axis of rotation, with a first scissor roll elevated relative to a second adjacent scissor roll. The separator screen is carried by the frame beneath at least one of the scissor rolls. The separator screen has a plurality of apertures for separating pieces having a size less than a predetermined size which pass through a shear outtake manifold for separation while preventing large subdivided pieces having a size greater than the predetermined size from passing therethrough. The recycle manifold section is provided within the enclosure downstream and above the scissor rolls. The subdivided pieces are passed through the set of scissor rolls and delivered to the recycle manifold section downstream and above the scissor rolls. The subdivided pieces are collected within the recycle manifold section and are delivered via a recycle flow path to one of the scissor rolls for further delivering and shearing of the subdivided pieces between the set of scissor rolls.
According to another aspect of the invention, an apparatus is provided for comminuting severable waste material into pieces. The apparatus includes a frame, a pair of overlapping scissor rolls, a screen, and a recycle manifold. The frame has an enclosure with an entrance opening for receiving the waste material. The pair of overlapping scissor rolls are rotatably carried by the frame. The scissor rolls are configured with substantially horizontal and parallel rotational axes with a first scissor roll communicating with the entrance opening and operative to feed the waste material between the first scissor roll and upward between the pair of scissor rolls. The first and second scissor rolls are operative to shear the waste material into smaller pieces as the material is passed between the scissor rolls from below. The screen is carried by the frame beneath the scissor rolls, and is configured to permit undersized smaller pieces of a size less than the predetermined size to pass therethrough and to prevent oversized smaller pieces of a size greater than the predetermined size from passing therethrough. The oversized smaller pieces are sheared into further subdivided pieces by passing upward between the scissor rolls. The recycle manifold is provided downstream and above the scissor rolls. The recycle manifold communicates with the second scissor roll. The recycle manifold is configured to receive the subdivided pieces passed between the scissor rolls, at least some of the subdivided pieces being delivered to the second scissor roll where they are again directed between the scissor rolls.
According to yet another aspect of the invention, a comminuting apparatus is provided having a frame, a set of overlapping scissor rolls, a first drive motor and a second drive motor. The frame has an enclosure with an entrance opening for receiving waste material. The set of overlapping scissor rolls is carried within the enclosure for rotation. The set of overlapping scissor rolls includes a first scissor roll and a second scissor roll. The first drive motor is coupled to the first scissor roll, and the second drive motor is coupled to the second scissor roll. The first drive motor is operative to drive the first scissor roll at a substantially variable operating speed. The second drive motor is operative to drive the second scissor roll in co-rotation at a substantially constant operating speed.
One advantage of the invention is provided in a simplified construction having a feedback control system for regulating delivery of material into the comminuting apparatus, and having enhanced recirculation features for recirculating material being comminuted therein.